Needle-bar vibrating mechanism



Feb. 16, 1943. A. R. WOOD 2,311,194

' NEEDLE-BAR VIBRATING MECHANISM Filed July 28, 1941- 3 Sheets-Sheet 1Aifred Mod Feb. 16, 1943. A. R. W000 NEEDLE-BAR VIBRATING MECHANISM 3Sheets-Sheet 2 Filed July 28, 1941 w a 4 4m? gr WW 5 Alfred IVboziFeb.'16, 1943. R, w o 2,311,194

- NEEDLE-BAR vmmwme MECHANISM Filed July 28, 1941 5 Sheets-She et s I 1fill/radii. "420d Patented Feblfi, 1943 2,311,194 7 NEEDLE-BAR VIBRATINGMECHANISM Alfred R. Wood, Bridgeport, Conn, assignor to The SingerManufacturing Company, Elizabeth, N. J., a corporation of New JerseyApplication July 28, 1941, Serial No. 404,283

7 Claims.

This invention relates to sewing machines and. more particularly, to theneedle-bar vibrating mechanism of sewing machines adapted to perform apredetermined sewing operation and then automatically come to rest.

The invention has for its primary object to provide improved mechanismfor automatically controlling the amplitude of needle-vibration atpredetermined periods in the stitching cycle.

Another object of the present invention is the provision of aneedle-vibration control device of a type adapted for convenientattachment upon existing assembled machines and designed particularlyfor automatically decreasing the amplitude of vibration of the needle atthe beginning and ending of the stitching cycle to produce groups oftying stitches effective for preventing raveling of the tack.

With the above and other objects in View, as will hereinafter appear,the invention comprises the devices, combinations, and arrangements ofparts hereinafter set forth and illustrated in the accompanying drawingsof a preferred embodiment of the invention, from which the severalfeatures of the invention and the advantages attained thereby will bereadily understood by those skilled in the art.

In the accompanying drawings, Fig. 1 is a side elevation, partly insection, of a Singer class 79 tacking machine embodying the presentinvention.

Fig. 2 is a top plan view of the bracket-arm of the machine.

Fig. 3 is a reverse side elevation of the gearing shown in Fig. 1. V

Fig. 4 is a top plan view, partly in section, of the gearing shown inFig. 3.

Fig. 5 represents an enlarged vertical sectional view takenlongitudinally of the bracketarm, illustrating the details of the headof the shaft carrying the needle-bar-vibrating crankmechanism, with thecrank-pin of the head at one extreme position of adjustment.

Fig. 6 is a sectional view similar to Fig. 5, but with the crank-pin atthe other extreme position of adjustment.

Fig. '7 is a disassembled perspective View of the parts shown in Figs. 5and 6.

Fig. 8 is an enlarged top plan of the improved cam attachment adaptedfor controlling the amplitude of needle-vibration, showing the method ofsecuring the same upon one of the existing gears in the sewing machine.

Fig. 9 is a vertical sectional view taken through screw 35.

the cam attachment and the gear upon which the sameis adapted to befastened.

Fig. 10 is an enlarged view illustrating the completed tack effected bya sewing machine equipped with the present invention.

The invention is designed more particularly for embodiment in theneedle-bar vibrating crank-mechanism of a sewing machine, such asdisclosed in the patent to E. B. Allen, No. 1,864,165, of June 21, 1932.The machine has the usual bed I, standard 2, overhanging arm 3 and head4. The stitch-forming mechanism comprises the reciprocating andlaterally vibrating needle-bar 5 carrying the eye-pointed threadedneedle 6. The needleebar 5 is journaled for endwise reciprocation in theswinging gate 1 which is mounted on pivot-pins 8 and derives itsvibratory movement from the main sewing shaft 9. The gate 1 is connectedby means of a link Iii to a slotted arm II which is fulcrumed at !2 onthe bracket-arm 3 and is connected by a link I3 to a crank-pin l4 fixedto a radially movable slide-plate carried by the rotary guide-head I 6formed at the upper end of a hollow shaft l1 journaled vertically in thebracketarm 3. The guide-head [6 receives step-'by-step rotae tionalimpulses through a train of gears l8 from the intermediatefeed-actuating shaft. [9 which carries a star-wheel 2|] with which meshthe pins 2| carried by the hub of a bevel-gear 22 mounted on the bearingpin 23 and driven by a bevelpinion 24 on the main sewing shaft 9. Thegear 22 is driven at half the speed of the shaft 9 and the gearing I8is. of such ratio that the guide-head It isgiven a half-rotation foreach impulse of the star-wheel received from one of the pins 2|. Theneedle-bar 5. is reciprocated by means of the usual crank 25 andlink-connection 26 with the main sewing shaft 9.

The hollow shaft 1 I has endwise slidably fitted therein a vertical rod21 having at its upper end an inclined portion 28 having fiat, paralleland inclined, edge-faces 29 in sliding engagement with the similarlyspaced parallel and inclined faces 3i: provided by plates 3| 32 mountedatthe under side of the slide-plate IS. The plate 3| is screwed fast ina fixed position to the slideplate. The plate 32 is secured to theslideeplate by screws 33 which pass through enlarged holes 34 in theslide-plate [5, giving clearance for limited adjustment of the p1atef32relative tov the plate 3| under the influence of the adjusting Theadjustment is so made as to eliminate lost-motion between the inclinedend 28 of the rod 21 and the plates 3i, 32, while retaining a freeworking fit. It will be understood that endwise movement of the rod 21will shift the slide-plate I 5 and crank-pin [4 diametrically of theguide-head I6 and vary the operative radius of the crank-pin. Themovement of the slide-plate I 5 is limited in one direction by astop-plate 35 which is fixed to one end of the slide-plate I5 inposition to engage the flat edge-portion 31 of the guide-head. Themovement of the slide-plate l5 in the opposite direction is limited by astop-screw 38 which is threaded into the guide-head l6 and held inadjusted position by the locking screw 39, see Fig. 7. The head of thestop-screw 38 is in position to be engaged by a stop-shoulder 40 on theslide-plate I5 (see Fig. '7).

The rod 2? is formed at its lower end with a neck 4| embraced by thefork 42 at one end of a pin 43 journaled in a boss 44 provided on thefree end of a lever 45 fulcrumed at 45 on the standard 2. Adjustablysecured to the lever 45 intermediate its ends by a screw-and-slotconnection 4'! is a follower 48 having an offset lower end 49 (see Fig.9) which engages and rides upon a needle-vibration control-cam securedto rotate with the gear-wheel 55 fixed to a vertical shaft 5| carryingthe main feed-cam 52 which is connected as usual to shift the regularwork-clamp 53. It will be understood that when the follower 48 ridesupon the upper surface of the controlcam on the gear-wheel 50 as shownin Fig. 9, the operative radius of the crank-pin I4 is increased to amaximum with a consequent maximum amplitude of vibration of the needle.In the machine chosen to illustrate the present invention thecontrol-cam is designed to maintain the needle vibration at maximumduring a major portion of each stitching cycle and at a minimum, orsubstantially zero, only during the formation of a few stitches at thebeginning and ending of each stitching cycle.

The needle-vibration control-cam, as used in the illustrated machine, isthe essence of the present invention. As shown in Figs. 8 and 9, thecontrol-cam comprises preferably a disk 54 formed with a horizontallydisposed flange 55 providing a primary cam-section, and a centrallylocated hub-receiving throat 55 opening laterally into the periphery ofthe flange 55, whereby the control-cam can be conveniently placed uponthe hub 51 of the gear-wheel 55. To rovide means for securing thecontrol-cam in proper position upon the gear-wheel hub, the body of thedisk 54 at opposite sides of the mouth of the hubreceiving throat 55 hasthreaded into it two setscrews 58 which, as shown in Fig. 8, areangularly arranged and are adapted at their inner ends to engage withone side of the gear-wheel hub 57. The two set-screws 58 are preferablylocated adjacent the opposite sides of the hub-receiving throat 56 andare spaced apart a distance greater than 180, as shown in Fig. 8, inorder that they will draw and clamp the cam firmly upon the hub of thegear 51.

Formed in the upper flat surface of the flange 55 is a concentric recess59 in which is slidably disposed for limited circular endwise adjustmenta supplemental or secondary cam-section 59 adapted to be maintained inadjusted position by a securing screw 6| passing through an elongatedaperture 52 in the secondary cam-section. The secondary cam-section 60at its leading end is bent downwardly, as at 63, in order that thefollower 48 when being approached by the camsection 59 will readilyclimb to a position on top of the cam-section. As clearly shown in Fig.9, the lower end 49 of the follower 48 is offset outwardly in order toprovide clearance for the securing screw 6 i It will be understood thatwhen the follower 48 is riding upon the secondary camsection 55 only theinner portion of the lower end of the follower engages the cam-section,and that after the secondary cam-section travels beyond the follower thelatter rides upon the narrow flat upper surface or primary cam-sectionof the flange 55. The follower 48 is biased into contact with theneedle-vibration control-cam by a spring-wire B4 coiled about a lug 65integral with the bracket-arm 3, one end of the springwire beinganchored by a screw 65 and the other end bearing downwardly upon theboss 44 provided on the end of the lever 45.

It will be observed that the adjustable secondary cam-section '60 isprovided for reducing the width of the mouth of the hub-receiving throat56 in order that the number of tying stitches produced at the beginningand ending of the stitching cycle may be controlled. The initially largemouth of the hub-receiving throat is necessary since theneedle-vibration control-cam has been designed for convenient attachmentupon existing machines without the necessity of disassembling thegearing. In attaching the illustrated needle-vibration control-cam uponthe gear-wheel 59, it is only required that the secondary cam-section 50be removed from the control-cam and the set-screws 58 unscrewed. Thecontrol-cam can then be placed upon the hub of the gear-wheel 55 andwhen properly located the set-screws 58 are tightened. The secondarycamsection 50 is then placed in position in the recess 59 and secured bythe screw 6 I.

Fig. 1 discloses the machine immediately after the starting lever hasbeen depressed and the machine has begun to perform its stitching cycleshown in Fig. 10. It will be observed that the lower end 49 of thefollower 48 is disposed substantially midway between the rear edge 61 ofthe mouth of the control-cam 54 and the inclined leading edge 63 of thesecondary camsection 60 and that it is in contact with the upper surfaceof the gear-wheel 50. When in this position the axis of the crank-pin I4is in substantial alinement with the axis of the hollow shaft I 1 (Fig.5); the amplitude of needle-vibration being at a minimum during suchalined position of the crank-pin and hollow shaft. After the formationof a predetermined number of superposed stitches, which function toeffectively lock the beginning end of the tack, the inclined leadingedge 63 of the secondary camsection 60 engages the follower 48 andraises the lever 45 against the action of the springwire 64. The raisingof the lever 45 shifts the crank-pin I4 to its position of maximumradius (Fig. 6), in which position the crank-pin l4 imparts to theneedle vibrations of maximum amplitude. The follower 48 rides upon theupper surface of the control-cam during the forma tion of the body ofthe tack, indicated as B in Fig. 10. At the proper time in the cycle,the follower 48 drops off the rear edge 61 of the control-cam into aposition controlled by the stop-plate 35. Immediately upon dropping offof the rear edge 61 the radius of operation of the crank-pin is reduced,to substantially zero, resulting in the formation of a plurality oftying st tches, indicated as T in Fig. 10, which serve to effectivelyprevent raveling of the completed tack. The stop-motion of the sewingmachine is adjusted so that the operation of the machine is interruptedwhen the follower 48 is substantially midway between the rear edge 61 ofthe mouth of the control-cam and the inclined leading edge 63 of thesecondary cam-section 60. When the machine comes to rest, the parts areso positioned as to repeat the above described stitching cycle when thestarting lever is depressed.

It will be understood that the location of the inclined leading edge 63and the rear edge 61 relative to the follower 48 determines the numberof tying stitches produced at the beginning and ending of the tack andthat by suitably adjusting these edges relative to the follower 48 andrelative to each other more or less tying stitches may be formed at thebeginning or ending of the tack. Also the number of the tying stitchesat the beginning and ending of the tack may be the same or different. Itwill be obvious that by shifting the inclined leading edge 63 so that itsubstantially touches the rear edge 61, no tying stitches will be made.

While the drawings illustrate a control-cam in which the narrow flatupper surface of the flange 55 on which rides the follower 48 is,throughout its length, at a uniform height above the upper surface ofthe gear-wheel 50, it will be understood that the narrow surface may becut so that it is at a varying height above the upper surface of thegear-wheel, in which case vibrations of different amplitude will beimparted to the needle. Such a control-cam could be employed forembroidery work in which case the stitch-design required would dictatethe shape of the narrow upper surface of the flange 55.

Having thus set forth the nature of the invention, what I claim hereinis:

l. A unitary needle-vibration control-cam adapted for convenientattachment upon a sewing machine having a vibratory needle and acam-actuated mechanism for controlling the amplitude of vibration ofsaid needle, comprising, a body-portion having a flange and asupport-receiving throat formed with a mouth opening into the peripheryof said flange, a primary cam-section on said flange, and a secondarycam-section having a portion thereof disposed in the mouth of saidthroat so as to extend the active portion of the control-cam to effectthe production of a predetermined pattern of stitches.

2. A unitary needle-vibration control-element adapted for convenientattachment upon assembled group-stitch sewing machines having avibratory needle and a cam-actuated mechanism for controlling theamplitude of vibration of said needle, comprising, a disk-likebody-portion adapted in operation to be rotated about an axis and havinga lateral flange and a support-receiving throat formed with a mouthopening into the periphery of said flange, a primary cam-section on saidflange, and a secondary cam-section mounted on said flange foradjustment relative to said primary cam-section about the axis ofrotation of the body-portion, said secondary cam-section having aportion thereof extending into the mouth of said support-receivingthroat in order to extend the active portion I of the control-element.

for controlling the amplitude of vibration of said needle, comprising, adisk-like body-portion adapted in operation to be rotated about an axisand having a lateral flange and a centrally located support-receivingthroat formed with a mouth opening into the periphery of said flange,

said lateral flange being formed with a recess concentric with saidsupport-receiving throat, a primary cam-section on said flange, asecondary cam-section mounted in said recess and having a portionthereof extending into the mouth of said support-receiving throat, andmeans for securing said secondary cam-section in said recess for limitedadjustment relative to said primary cam-section in order to regulate theactive portion of the control-element.

4. A unitary needle-vibration control-element adapted for convenientattachment upon assembled group-stitch sewing machines having avibratory needle and a cam-actuated mechanism includin a gear having ahub for controlling the amplitude of vibration of said needle,comprising, a disk-like body-portion having a laterally extendinghorizontal flange and a hub-receiving throat formed with a mouth openinginto the periphery of said flange, said flange being provided in itsupper surface with a recess concentric with the hub-receiving throat, aprimary cam-section on said flange, a secondary cam-section mounted 3 insaid recess and having a portion thereof extending into the mouth ofsaid hub-receiving throat, the portion of said secondary cam-sectionextending into said recess having an elongated aperture formed therein,and a screw passing through said elongated aperture and threaded intosaid horizontal flange for adjustably securing said secondarycam-section in operative position.

5. A unitary needle-vibration control-element adapted for convenientattachment upon assembled group-stitch sewing machines having avibratory needle and a cam-actuated mechanism for controlling theamplitude of vibration of said needle, comprising, a disk-likebody-portion having a laterally extending flange and a supportreceivingthroat formed with a mouth opening into the periphery of said flange,means including a pair of screws threaded into said body-portion forsecuring said unitary control-element upon its supporting member, aprimary cam-section on said flange, and a secondary cam-section mountedon said laterally extending flange and having one end thereof projectinginto the mouth of said support-receiving throat to increase the lengthof the active portion of the control-element.

6. A needle-vibration control-element adapted for convenient attachmentupon group-stitch sewing machines having a vibratory needle and, acam-actuated mechanism for controlling the amplitude of vibration ofsaid needle, comprising, a

0 disk-like body-portion having a laterally projecting flange and asupport-receiving throat formed with a mouth opening into the peripheryof said flange, securing means for said control-element including a pairof screws threaded into said body-portion in angular relationship and,having their inner ends extending into said supportreceiving throat andadapted to engage the control-element supporting member, a primarycamsection on said flange, and a secondary camsection mounted on saidlaterally projecting flange and having one end thereof extending intothe mouth of said support-receiving throat to increase the length of theactive portion of the control- 75 element.

7. A unitary control-element adapted for con venient attachment uponassembled sewing machines, comprising, a body-portion having a laterallyextending flange and a support-receiving throat formed with a mouthopening into the periphery of said flange, means including a pair ofscrews threaded into said body-portion for securing said control-elementupon its supporting member, a primary cam-section on said flange,

a s'eeondary cam-section mounted on said laterally extending flange andhaving one end thereof projecting into the mouth of saidsupport-receiving throat to increase the length of the active portionofth control-element, and means adjustably securing said secondarycam-section on said flange.

ALFRED R. WOOD.

